Blogs, like any written material, have a shelf-life. Some are short-term, others are long-term, and most of us, whether intentional or not, write both versions. Think about literature. Most of us could name a book by Charles Dickens, or Mark Twain or Edgar Allen Poe. I imagine seeing those names immediately stirred a title or a quote in your mind. I went to "The Raven" instantly.
Now, think about the one million books you find on Amazon. How many authors or titles can you think of close to a million. Probably not many, though you may know a bunch. Why? Of course, you haven't been exposed to most, but why would you know A Christmas Carol and not Objective-Oriented Java Script by Ved Antonia and Stoyan Stefnor? Two reasons, basically. One, A Christmas Carol is a timeless tale about life. It continues to inspire the good in all of us, whereas, Objective-Oriented Java Script is not something that affects everyone of us and it is valuable for a period in time.
Your blogs are just like that. Look back through your blog roll and see which ones rank the highest. I bet you find that they are the ones that will be timeless (at least to a point). They will be about clients relations, circumstances, both good and bad, and how you handled them, techniques to secure leads and things that affect your daily life. They will be local sights and historically important things about your community. They will be about emotion and triumph.
I still remember a line by Dick Greenberg from many years ago encouraging us to "be the pig." But, I don't remember Dick's market reports. I know he does great ones, and I'm always impressed with his content and format, and I've followed in his footsteps, but why don't I remember them? They're not for me. They're for people searching for homes in Fort Collins, CO.
Now, look at the low ranking blogs. They will be about market reports and local events. They rank high for the immediate time around the release and then they trim off hits as time moves away from the information. And, you know what? That's how they're designed. They are to attract the attention of the "then interested" web-searcher who is trying to gather information about your community.
Those types of blogs are short-term. They serve a very distinct purpose, and when that purpose is fulfilled, they will garner minimal attention, but that is what Objective-Oriented Java Script is all about. It's answering questions for the moment. It's important to those who need that information right now. They won't need it in five years. They need it today.
You want to write both types of blogs. You want some to be timeless (or as timeless as possible), and you want some to be short-term. Both have an audience, and both draw attention to your wit, wisdom and expertise. I encourage everyone to write market reports and about local events. They're the Java Script of the real estate world, but you should also write about great client relations, extraordinary events and cats. People love reading about cats, but they also want an agent who is great to work with. Blogs have a lifespan and you are nurturing it on both ends of it.